South Lake Tahoe, CA has a population of 21,506 and is the 2,020th largest city in the United States. The population density is 2,117 per sq mi which is 811% higher than the California average and 2236% higher than the national average. The median age in South Lake Tahoe is 38 which is approximately 6% higher than the California average of 36. In South Lake Tahoe, 47% of the population over 15 years of age are married, 67% speak English and 26% speak Spanish. 53% of South Lake Tahoe residents were born in California, 24% were born out of state, 3% were born outside of the United States and 20% were foreign born.